• [ 'S ] 



rate and fkilfully conduded analyfis of Dodor Kennedy, who 

 bids fair to rival the excellence attained by the greateft mafters 

 of that fublime and difficult art. 



Experiment the Jirji. 



Gfunflen a compound of felfpar and hornblende intimately 

 mixed with each other, was the fubjedt of this experiment. Its 

 colour, black or greenifli black intermixed with pale reddifli brown ; 

 both the felfpar and hornblende imperfedly and confufedly cryf- 

 tallized in minute grains ; the JraSfuri partly ftriated and partly 

 foliated. Litflre moderate, its hardnefs 7, or almoft 8, gives an 

 earthy fmell when breathed upon, and frequently contains fmall 

 fpecks of pyrites, ibid. p. 7. 



This fubftance he vitrified by a ftrong heat and fubfequent 

 rapid cooling, p. 9. A fragment of the glafs thus produced being 

 introduced under a narrow muffle and heated to 21" in one mi- 

 nute became fo foft as to yield readily to the preffure of an iron 

 rod, but after a fecond minute it became quite hard though the 

 temperature had ' been flationary ; the fubftance thus hardened 

 underwent a thorough change, it loft its vitreous charader, its 

 frafture Was like that oi porcelain (that is even) and it was fufiblc 

 only in a heat of 31'' p. 11. In another experiment, (ibid.) he 

 found this change to take place even before the glafs was in per- 

 fed fufion i fo^ while both ends of a fragment of this glafs were 



fupported 



